Male Infertility May Have Obesity Link

Sept. 1, 2006 -- New research shows a possible link between male infertility and obesity.

The link -- based on male BMI (body mass index, which relates height to weight) -- hasn't been proven and needs further study, the researchers stress.

"To our knowledge this was the first study to examine male BMI and couple fertilityfertility. Thus, it is important that the findings will be confirmed or refuted in future studies," researcher Markku Sallmen, PhD, tells WebMD in an email.

Sallmen worked on the study while at the U.S. National Institute of Environmental Health Sciences and is now based at the Finnish Institute of Occupational Health in Helsinki, Finland.

The study appears in Epidemiology's September edition.

Complex Issue

It's often hard to pin down the source of infertility. Men and women may each have risk factors for infertility.

For instance, women may have a harder time conceiving as they near the end of their childbearing years.

Also, "it is well documented that women who are overweight or obese are at higher risk of reproductive problems, including reduced fertility," the researchers write.

But little has been known about what effect, if any, men's BMI has on infertility, Sallmen's team notes.

Sallmen and colleagues studied 2,111 couples in Iowa and North Carolina. The men in those couples were mainly farmers; their wives were less than 40 years old.

The researchers asked the men's wives about infertility, defined as not conceiving a pregnancypregnancy after at least 12 months of unprotected sex in the previous four years, even if the wives later got pregnant.

The husbands and wives reported their height and weight. The researchers used that data to calculate BMI.

The couples didn't get checkups or infertility tests for the study.

But the researchers noted factors including the wives' BMI and the age, smoking status, alcohol use, and exposure to solvents and pesticides for husbands and wives.